Comparison of Molecular Subtypes of Carcinoma of the Breast in Two Different Age Groups: A Single Institution Experience.

Background Hormonal analysis and molecular subtyping are used as an important predictive and prognostic factors in women with carcinoma of the breast. The aim of this study was to analyze and compare the hormonal (estrogen receptor (ER) and progesterone receptor (PR)) and human epidermal growth factor (HER2) status among women with carcinoma breast belonging to two different age groups and classify them in molecular subtypes (luminal A, luminal B, triple negative, and HER2). Materials and Methods This was an analytical cross-sectional study performed at a tertiary care center in Northern India. Breast carcinoma cases treated over a period of two years were stratified into two groups (≤ 40 years: younger group, n = 27 and > 40 years: older group, n = 33). Their hormonal (ER, PR) and HER2 status were studied using immunohistochemistry (IHC) and classified according to the molecular classification of the breast carcinoma. Results A total of 60 cases of breast carcinoma were treated for hormonal and HER2 status during our study period and were classified into four subtypes. In the younger group (n = 27), luminal A (n = 16, 59.2%) was the most common molecular subtype, followed by triple negative (n = 6, 22.2%), HER2 (n = 4, 14.8%), and luminal B (n = 1, 3.7%). Similarly, in the older group luminal A (n = 20, 60.6%) ranked first, followed by triple negative (n = 10, 30.3%), HER2 (n = 2, 6.0%), and luminal B (n = 1, 3.0%). Conclusion Carcinoma of the breast in young women shows variation in the prevalence of molecular subtypes in different regions of the world. The results of our study are in accordance with the Asian literature, showing no significant difference in molecular subtyping of carcinoma breast in younger versus older women. More molecular research is needed to clearly understand the pathophysiology associated with carcinoma of the breast in young women.